Carbohydrates and Lipids

Carbohydrates and Lipids Carbohydrates Outline the structural organisation of carbohydrates (monomer → polymer) Monosaccharides are joined together by condensation reactions to form polysaccharides (water produced) ………………………………………………………………………………………………………………………………………………….......... The covalent bond connecting the monosaccharides together is called a glycosidic linkage ………………………………………………………………………………………………………………………………………………….......... Polysaccharides can be digested into smaller oligosaccharides via hydrolysis reactions (water is required) ………………………………………………………………………………………………………………………………………………….......... List three examples of monosaccharides, disaccharides and polysaccharides Glucose, Galactose, Fructose (Hint: Gives Good Flavour) Monosaccharides: ………………………………………………………………………………………………………………………... Disaccharides: ………………………………………………………………………………………………………………………... Polysaccharides: ………………………………………………………………………………………………………………………... Lactose, Sucrose, Maltose (Hint: Length Supports Movement) Cellulose, Glycogen, Starch (Hint: Can Get Stored) List three functions for carbohydrates within cells Short-term energy source (e.g. glycogen and starch) 1. …………………………………………………………………………………………………………………………………………………... Structural component (e.g. cellulose in plant cell walls) 2. …………………………………………………………………………………………………………………………………………………... Cell recognition and signalling (e.g. glycoproteins in plasma membranes) 3. …………………………………………………………………………………………………………………………………………………... Complete the following table comparing different polysaccharides of glucose Monomer Bonding Shape Cellulose ß-glucose 1-4 linkages linear (sheets) structural component of plant cell walls Amylose α-glucose 1-4 linkages linear (helical) short-term energy storage in plants (type of starch) α-glucose 1-4 linkages AND 1-6 linkages less branched (~per 20 units) short-term energy storage in plants (type of starch) α-glucose 1-4 linkages AND 1-6 linkages more branched (~per 10 units) short-term energy storage in animal cells Amylopectin Glycogen Function Lipids Identify the main classes of lipids by completing the flow chart below Lipids Simple lipids Esters of fatty acids Compound lipids Esters of fatty acids and other group triglycerides, waxes phospholipids, sphingolipids, etc. Derived lipids Composed of hydrocarbon ring steroids, cholesterol List five different functions of lipids Storage of energy (e.g. triglycerides) S …………………………………………………………………………………………………………… Hormonal role (e.g. steroids) H …………………………………………………………………………………………………………… Insulation (e.g. sphingolipids) I …………………………………………………………………………………………………………… Protection of organs (e.g. triglycerides, waxes) P …………………………………………………………………………………………………………… Structural component (e.g. phospholipids) S …………………………………………………………………………………………………………… Compare the use of carbohydrates and lipids (triglycerides) as energy sources triglycerides = long-term energy storage ; carbohydrates = short-term energy storage Storage: ………………………………………………………………………………………………………………………………………… triglycerides have less effect on osmotic pressure (they are hydrophobic / not a solute) Osmotic Effect: ……………………………………………………………………………………………………………………………… carbohydrates are easier to digest (more readily consumed and can be digested anaerobically) Digestion: ……………………………………………………………………………………………………………………………………… lipid digestion has a higher ATP yield (~twice as much energy per gram) ATP Yield: ……………………………………………………………………………………………………………………………………… triglycerides are insoluble in water and hence harder to transport Solubility: ……………………………………………………………………………………………………………………………………… Explain why carbohydrates and lipids are used preferentially to proteins as an energy source Protein digestion produces nitrogenous wastes (due to the presence of an amine group) ………………………………………………………………………………………………………………………………………………….......... Nitrogenous wastes are toxic to cells (must be removed via excretion by the kidneys) ………………………………………………………………………………………………………………………………………………….......... Differentiate between saturated and unsaturated fatty acids Saturated fatty acids do NOT have double bonds (possess maximal amount of H atoms) ………………………………………………………………………………………………………………………………………………….......... Unsaturated fatty acids possess double bonds (may be monounsaturated or polyunsaturated) ………………………………………………………………………………………………………………………………………………….......... Contrast cis and trans isomers Cis Isomer H atoms on the same side of the double bond ………………………………………………………………………… Double bond creates kink in fatty acid chain ………………………………………………………………………… Are loosely packed and usually liquid ………………………………………………………………………… Occurs commonly in nature ………………………………………………………………………… Generally considered good for health Trans Isomer H atoms on opposite sides of the double bond ………………………………………………………………………… Double bond does NOT create kink in chain ………………………………………………………………………… Are tightly packed and usually solid ………………………………………………………………………… Occurs in processed foods ………………………………………………………………………… Generally considered bad for health ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… ………………………………………………………………………… Identify the role of high density and low density lipoproteins Low density lipoproteins (LDLs) transport cholesterol from the liver to the rest of the body ………………………………………………………………………………………………………………………………………………….......... High density lipoproteins (HDLs) scavenge excess cholesterol and return it to the liver for disposal ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Outline the effect of different types of fatty acids on lipoprotein levels Cis fats raise levels of HDL (lowers blood cholesterol) ………………………………………………………………………………………………………………………………………………….......... Saturated fats raise levels of LDL (raises blood cholesterol) ………………………………………………………………………………………………………………………………………………….......... Trans fats raise levels of LDL and lower levels of HDL (significantly raise blood cholesterol) ………………………………………………………………………………………………………………………………………………….......... Cis fats are generally considered good for health, saturated and trans fats are considered bad for health ………………………………………………………………………………………………………………………………………………….......... Describe the health implications associated with high levels of blood cholesterol High cholesterol levels lead to hardening and narrowing of the arteries (atherosclerosis) ………………………………………………………………………………………………………………………………………………….......... The cholesterol forms fat deposits in the arterial lining, leading to the development of plaques ………………………………………………………………………………………………………………………………………………….......... If a plaque ruptures, blood clotting will cause the vessel to become blocked ………………………………………………………………………………………………………………………………………………….......... If coronary arteries become blocked, coronary heart disease will result (including heart attacks, etc.) ………………………………………………………………………………………………………………………………………………….......... Discuss the evidence for (and against) health risks associated with diets rich in lipids Evidence for: ………………………………………………………………………………………………………………………………………………….......... A positive correlation exists between intake of saturated fats and incidence of CHD ………………………………………………………………………………………………………………………………………………….......... Intervention studies demonstrate that lowering intake of saturated fats reduces onset of CHD ………………………………………………………………………………………………………………………………………………….......... In patients who have died from CHD, fatty deposits with high levels of trans fats were found in arteries ………………………………………………………………………………………………………………………………………………….......... Evidence against: ………………………………………………………………………………………………………………………………………………….......... Certain populations have high fat intakes but low rates of CHD (e.g. Maasai tribe in Africa) ………………………………………………………………………………………………………………………………………………….......... Genetic factors play a significant role (blood cholesterol levels only show a weak association to diet) ………………………………………………………………………………………………………………………………………………….......... Results from intervention studies are influenced by cohort size and composition, as well as study duration ………………………………………………………………………………………………………………………………………………….......... Use the information included below to assess the weight of individuals according to BMI categories Underweight Normal Weight Overweight Obese (Class I) Obese (Class II) Obese (Class III) <18.5 18.5 – 24.9 25.0 – 29.9 30.0 – 34.9 35.0 – 39.9 >40.0 Individual 1: Height = 175 cm Weight = 65 kg 65 ÷ (1.75 x 1.75) = 21.22 BMI: ……………………………………………………… Individual 2: Height = 190 cm Weight = 130 kg 130 ÷ (1.9 x 1.9) = 36.01 BMI: ……………………………………………………… Individual 3: Height = 165 cm 50 ÷ (1.65 x 1.65) = 18.37 Normal weight Category: …………………………………………………………….. Obese (Class II) Category: …………………………………………………………….. Weight = 50 kg BMI: ……………………………………………………… Under weight Category: ……………………………………………………………..